The MFJ-752DSignal Enhancer II is a dual tunable audio filter that permits you to zero in on a single sideband and Morse code signal and notch out interference at the same time. It can also be used for AM mode shortwave listening. The primary filter is a two section, four-pole variable filter with Peak, Notch, Low Pass and High Pass functions. There is also an auxiliary filter which is a single section two-pole Peak and Notch filter. These two independent filters allow you to remove interference while enhancing the desired signal. The filter is automatically bypassed when the unit is off. There are RCA phono jacks on the back panel for two selectable audio input sources. There is also a speaker RCA phono jack and a 3.5mm mini headphone jack.